Japanese knife steels-WTF
- Delucacheesemonger Aug 13, 2013 09:54 AM
Have decided to add a few Japanese knives to my knife collection and am baffled by the descriptions of 61 carbon steel, white steel, blue steel with tungsten, etc. The knives l use now are primarily relatively soft carbon steel and l love them as they are easy to sharpen. My current Japanese knives purchased at the two Masamoto stores in Tsukiji, l have sharpened at Korin in New York.
These will be used sparingly and most definitely not professionally thus would like a brief explanation of the differences in the steels involved and suggestions in which to get.
As of now l plan on a sujihiki or a yanagiba at 300 mm or 330 mm.
This is primarily directed at Cowboyardee,Chemicalkinetics, Knifesavers, and Kaleokahu but all are welcome
Thanks for your help.
A basic primer in Japanese carbon steels:
White steel = shirogami
Blue steel = aogami
Yellow steel = kigami
White steel tends to be the easiest to sharpen of the three. It doesn't quite have the edge retention or corrosion resistance of blue steel (which has chromium and tungsten added). Blue steel tends to have greater wear resistance. Supposedly, blue steel is a little more chip prone than white steel, but in practice it depends more on the knife in question and the hardness it's tempered to than which steel you're using. You won't see too much yellow steel in the knives you're looking at, I think. Yellow steel is generally thought to be less desirable than white or blue steel, though in practice none of the three are bad.
Slightly complicating matters, white and blue steels each come in three formulations.
- White #1 (most carbon, usually considered the best white steel, most expensive white steel, sharpens extremely well)
- White #2 (a bit less carbon than white #1, still sharpens well, still a good steel)
- White #3 (a bit less carbon than white #2, still pretty decent)
- Blue super steel (also known as AS for 'aogami super,' high carbon, high wear resistance, great edge retention, harder to sharpen than white steels)
- Blue #1
- Blue #2 (least corrosion resistance, least edge retention, and easiest to sharpen of the blue steels)
In practice, all of these are good steels. Keep in mind that hardness can vary and can also play just as much or more of a role in how these steels sharpen or perform than their comparative makeups.
"High carbon steel" is a pretty general term and could indicate any of the above. But more likely, none of the above (if they were using blue or white hitachi steel, they'd probably advertise it). Could even be a stainless steel. Impossible to say. Your best bet would be to ask the vendor. Not particularly familiar with yoshiharu knives. Sorry I can't help you there.
In addition to what cowboyardee said, there's also super blue ( which is a combination of white and blue steel) and SK4 or SK5 which is a budget or low end carbon steel.
Bluewayjapan sell Yoshiharu knives, the ones that are listed as high carbon are likely made from SK4/5 or yellow steel. FWIW, SK4/5 steel is notorious for being very reactive and taking forever to develop a patina; it would be fine for a protein only knife like a Sujihiki, but a pita on knives that see a lot of acidic foods.
Yanigaba is ideally suited for cutting sushi and other soft items. If you want one, get one that is made from white#2 or better. The ones made from lesser steels, won't provide the type of edge that a yanigiba needs, plus low-end single bevel knives are more opt to bent, warped, and/ or poorly ground.
If you aren't doing sushi, and are just looking for a general purpose slicer, get a Sujihiki.
The alloys are all *slightly* different in composition and attributes. Hardness itself is mostly a function of the heat-treat.
If you want Hitachi steel, I like ATS34 which is a stainless toolsteel, basically the same as 154cm. The HT is complicated and hard to get right. Their SLD-Magic is another I'd like to try.
<The knives l use now are primarily relatively soft carbon steel and l love them as they are easy to sharpen>
I actually do not find there is a huge difference between sharpening a harder steel knife vs a softer steel knife. You may spend a bit more time, but they require the same skill set. We are not talking about night and day difference -- unless you are talking about single bevel vs double bevel knives, but that has to do with geometry.
<My current Japanese knives purchased at the two Masamoto stores in Tsukiji>
You still want more?
<As of now l plan on a sujihiki or a yanagiba at 300 mm or 330 mm>
Sujihiki is easier to use. Unless you have a strong preference, then go with it.
If you are going to get a Japanese knife, then you may as well get the white steel (shirogami) or a blue steel (aogami). Usually speaking, blue steel is a bit more expensive, but it is a bit easier to take care of -- less easy to get rusted...etc. However, both are really great.
There are many variation within white steel and blue steel, but I won't worry too much at this point unless you are set to get the absolutely best possible knife. Again, what is best for you, may not be best for me. Most sushi chefs prefer white steel because it is slightly easier to sharpen and it is rumored to take on a slightly sharper edge. However, I prefer blue steel knives because they are slightly easier to take care of.
Some more food for thought. Any decent Japanese knife, even the ones made from lower grade steels (SK4/5, Yellow, etc.) will be tempered harder, take and hold a sharper edge, have a thinner, lighter weight blade, etc. than a typical European steeled knife. Just know, low grade carbons are more prone to rust and acid food reactions, so their upkeep is higher and may not be the best choice for knives that see a lot of acidic foods.
Whites and Blues will take a sharper edge and hold it longer, and aren't a pita to maintain as the lower grade steels. I like both a lot and will lean towards Whites for knives that mostly see soft targets and /or little board contact, Blues for general purpose tasks.
To date, i can get White sharper, with less effort than other steels, but their crazy sharp edge doesn't last very long. Blue takes longer to sharpen, and will hold an edge much longer than White. I can get Blue almost as sharp as White ( doing my regular routine), or as sharp as White ( by refining the edge ALOT on the finishing stone, loaded strop).
Both White and Blue #1 take longer to sharpen, and have better edge retention than White and Blue #2, but the differences between a #1 vs. #2 White or Blue, and White vs Blue are quite subtle. You really have to be a knife nerd, live with them and sharpen them several times to tell them apart.
They're all good, just a little different.
i had posted a link to a blog post i had written about these steels here earlier, but it seems it was deleted because i just posted the link... here's what i was trying to link to:
A Quick Summary of Hitachi Carbon Steels Common in Knives
Hitachi makes a number of carbon steels. Here are the common ones found in knives.
SK Steels (sk5, sk4, sk3)- the least expensive of the carbon steels and the lowest carbon content (#5 has the least carbon, #3 the most). This steel has higher amounts of phosphorus and sulfur than the other steels i'm about to mention. This steel tends to be tough (due to the lower carbon content and thus lower hardness). It also tends to be more reactive.
Yellow Steel (yellow 3, yellow 2)- This steel is more pure (less phosphorus and sulfur than the SK Steels). It also has higher carbon content (#3 has less carbon than #2 in this case as well). This steel is commonly found in saws and wood working tools. It is also sometimes found in knives.
White Steel (White 3, white 2, white #1)- This steel is even more pure than yellow steel (which is relatively pure). Once again, the lower the number, the higher the carbon content, so white #1 has the most carbon and white #3 has the least. The higher carbon (and hardness) leads to white #1 having the best edge retention of the white steels and also the best ability to hold an acute angle. White #3 has the best toughness.
Blue Steel (Blue #2 and Blue #1... i'll talk about blue super later)- Blue steel is white steel with chromium and tungsten added to it. Blue #2 has the same amount of carbon as white #2 but has the added elements. Same for blue #1 and white #1. The added elements lead to better corrosion resistance and edge retention (as well as deeper hardening). This also comes at the cost of being more difficult to sharpen and not taking quite as keen of an edge. Blue steel also tends to be more brittle (ever so slight).
Blue Super- Blue super is blue #1 with even more carbon, chromium, and tungsten added to it. Its the best of the hitachi carbon steels with regard to edge retention and ability to hold an acute angle (due to the higher carbon/hardness and added elements). This comes at the cost of being more difficult to sharpen, not getting quite as sharp, and being the most brittle of the bunch.
So, in conclusion, the white steels take the best edge (#1 holding the most acute angle and #3 being the toughest), while the blue steels hold the best edge (Blue super being the best at this while blue #2 and #1 have better toughness).
sujihiki can be made in a wide variety of sizes, but the most common are 270mm, followed by 300 and 240mm. Larger or shorter than that are not commonly used, as they are often too big or too small for the tasks commonly done by sujihiki. Even when i was in professional kitchens, 330mm would have been overkill for anything we did. 270mm was just right, and 300 was ok too.